i've been looking for this hentai manga for quite a while now, a little sister creeps out to his older brothers room, and man she has an ultimate sex drive she just wants sex, anyways her brother's reluctant at first but then agrees. The manga had 2 volumes. in the second volume she somehow cheats and have sex with the school PE teacher, the brother witness this and feels sad, in the end i remember the teacher saying "my child bearing student"

Also this manga had an English title, but i can't remember.

Thanks in advance.

Before Sunrise and Before Sunset by Maruwa Tarou

Translated by FUKE.

Yep that's it! thank you very much!